Exam 3 (a&p)

Provide two characteristics that distinguish skeletal muscle tissue from smooth muscle tissue.

1) Smooth muscle tissue lacks striations that are visible in skeletal muscle tissue. 2) Smooth muscle cells are spindle-shaped with a single, centrally located oval nucleus while skeletal muscle cells are long and multinucleated.

List at least three muscles that contribute to smiling.

Zygomaticus major and minor, orbicularis oris, and risorius

A triad consists of:

a transverse tubule (T-tubule) and two terminal cisternae

Latissimus dorsi

back (4)

Triceps brachii

back of arm (1)

Vastus medialis

between inner thigh and bone (3)

) The quadriceps femoris group includes all of the following EXCEPT

biceps femoris

Pectoralis minor

boob (6)

When walking, which muscle flexes your forearm?

brachioradialis

Which muscle assists with the erection of the penis and clitoris?

bulbospongiosus

What is required for excitation-contraction coupling?

calcium ions and ATP

Gastrocnemius

calf (2)

The masseter and temporalis muscles provide much of the force for

chewing

The levator ani inserts on the

coccyx

Damage to which of the following muscles would interfere most with the ability to breathe?

intercostals

The type of contraction in which length of the muscle fibers do not change is called:

isometric.

What type of contraction requires the greatest amount of tension?

isotonic eccentric contraction

Larry's muscles weakened while he played tennis for hours on a hot summer afternoon. This inability to maintain intensity is defined as:

muscle fatigue.

Which protein does NOT belong in a thin filament?

myosin

Smooth muscle and skeletal muscle both possess

myosin and actin filaments.

Pectineus

near pelvis (1)

Platysma

neck (5)

The synapse of a motor neuron with a muscle fiber is known as the:

neuromuscular junction.

Which muscles forms the anterior surface of the neck?

platysma

A muscle cell experiencing resting membrane potential is:

polarized

Muscles that move the thumb will be named using the term:

pollicis

Which of the following muscles is named for its shape? A) triceps brachii B) pronator quadratus C) vastus medialis D) levator scapulae

pronator quadratus

Which group is an antagonist to the hamstrings group?

quadriceps femoris group

Jorge tried to pick up his sofa but discover that it is much heavier than he expected. What must occur in the muscle to increase tension so he can pick up this heavy piece of furniture

recruitment of additional motor units

The increase in muscle tension that is produced by increasing the number of active motor units is called:

recruitment.

The superior aspect of the pubic bones is the origin of:

rectus abdominis

Which muscle is the agonist for sitting up?

rectus abdominis

Which of the following muscles does NOT adduct the thigh?

rectus femoris

Which of the following muscles extends the knee?

rectus femoris

The muscle named gluteus maximus tells us two facts: 1) it is located in the buttocks (gluteus), and 2) it is a large muscle (maximus).

true

The pharyngeal constrictor muscles propel food from the throat into the esophagus when swallowing.

true

The return of calcium ions to the sarcoplasmic reticulum during muscle relaxation decreases the calcium ion concentration in the cytosol.

true

The soleus is a synergist of the gastrocnemius during plantar flexion

true

The superiorly positioned spinalis and longissimus groups of the erector spinae muscles each have a capitis muscle, cervicis muscle, and thoracis muscle.

true

The three types of myofilaments are thin, thick and elastic.

true

The union of the muscles of the quadriceps femoris group forms the quadriceps tendon, which continues on to form the patellar ligament.

true

Type IIb fibers produce the fastest, strongest twitches of any fiber type.

true

Which fiber type helps Frances stand for hours in her job as a nurse?

type I fiber

The fastest muscle contraction would be produced by a:

type IIb fiber.

Gluteus medius

upper butt (5)

Which of the following muscles is named using a directional term? A) orbicularis oris B) vastus lateralis C) gastrocnemius D) adductor longus

vastus lateralis

What characteristic is NOT descriptive of cardiac muscle tissue?

voluntary muscle contractions

What anchors thin and elastic filaments in place within the myofibril?

z disc

Which muscle assists with smiling?

zygomaticus major

An agonist is a muscle that provides most of the force required for a given movement.

true

Most levers in the human body are:

) third-class levers

Each of the following muscles acts to flex the leg, EXCEPT:

) vastus lateralis

What value best represents resting membrane potential of skeletal muscle cells?

-85 mV

Place the following events of excitation in the correct order. 1) ion channels on the sarcolemma open and sodium ions enter the muscle fiber 2) the entry of sodium ions into the muscle fiber depolarizes the sarcolemma locally 3) acetylcholine is released from vesicles in the motor neuron into the synaptic cleft 4) an action potential arrives at the axon terminal of a motor neuron 5) acetylcholine binds to ligand-gated sodium ion channels in the motor end plate

4, 3, 5, 1, 2

Explain how a lever system can work at a mechanical disadvantage but still be useful in moving a load. What type of lever system fits this description?

A lever system that operates with the load far from the fulcrum and the effort applied near the fulcrum is operating at a mechanical disadvantage in terms of power. Third-class levers work at a mechanical disadvantage. Although third-class levers have a disadvantage in terms of force, they exchange it for advantages in speed of movement and distance through which the load is moved.

Explain where sodium and potassium ions are relative to a muscle cell during resting membrane potential

A membrane is considered polarized in its resting state when opposite charges are located on either side of the membrane. At rest, the concentration of sodium ions is greater in the extracellular fluid and lower in the cytosol due to the actions of the Na+/K+ ATPase pump. Potassium ion concentration is higher in the cytosol and lower in the extracellular fluid at rest

Cindy's leg muscles displayed a state of hypotonia since her arm was recently removed from a cast

true

List and describe the types of contractile and regulatory proteins found in a thin filament.

A thin filament is composed of actin, tropomyosin, and troponin. Actin is a contractile protein. Actin has an area known as an active site that can bind a myosin head. Strings of actin molecules form the largest part of the thin filament. Tropomyosin is a regulatory protein that spirals around the actin strands and covers the active sites. Troponin is a second regulatory protein that holds tropomyosin in place and binds a calcium ion.

Where should most of the potassium ions be located when a muscle cell is at rest?

A) cytosol of the muscle cell

What are possible products of glycolytic, or anaerobic, catabolism?

ATP, pyruvate, and lactic acid

excitability

Ability of muscle cells to respond to stimuli

extensibility

Ability of muscle cells to stretch

elasticity

Ability of muscle tissue to return to its original shape after being stretched

contractility

Ability of proteins within the muscle cells to draw together

Explain the role of acetylcholine in the excitation phase of excitation-contraction coupling.

Acetylcholine is a neurotransmitter responsible for triggering changes in skeletal muscle cells. When released by axon terminals into the synaptic cleft, acetylcholine binds to ligand-gated ion channels in the motor end plate of the skeletal muscle. Upon binding the receptors, sodium ion channels open and sodium ions enter the muscle fiber to produce a local depolarization in the skeletal muscle leading to the muscle cell's action potential

The nerve gas, sarin, was used during World War II as chemical warfare. Sarin inhibits the effects of acetylcholinesterase at the synapse. Predict how sarin will affect excitation.

Acetylcholinesterase promotes muscle relaxation by degrading acetylcholine that remains in the synaptic cleft. Acetylcholinesterase breaks down the acetylcholine into substances that can no longer stimulate the muscle. Without adequate acetylcholinesterase available to perform this job, acetylcholine will continue to excite the muscle cell by binding to ligand-gated sodium ion channels in the motor end plate. Ion channels will open and the entry of sodium ions into the muscle cell will create a local depolarization. Muscles will be unable to relax if acetylcholine is continually present in the synaptic cleft without the degrading effects of acetylcholinesterase.

Decreased oxygen availability leads to muscle fatigue.

true

Describe the relationship between agonists and antagonists

An agonist, or prime mover, is a muscle that provides most of the force for a given movement. Antagonist muscles usually lie on the opposite side of a joint from its agonist partner. The antagonist tends to slow and oppose the action of the agonist.

Explain how synergists and antagonists balance the action of the agonist.

An agonist, or prime mover, provides most of the force required for a given movement. Antagonists usually lie on the opposite side of the joint from its agonist partner and acts to oppose and slow the action. Slower, more graceful movements result from highly controlled actions by antagonists. Synergists work together with the agonist and sometimes make a movement more efficient by stabilizing a joint, overlapping with the role of the next group.

Determine the type of muscle contraction needed to lower a heavy bowling ball down by your side so you can roll it down the lane

An isotonic eccentric contraction results in muscle lengthening and is the type of contraction that allows you to lower a heavy load. Motor units must generate tension while the sarcomere stretch and lengthen.

Explain how a sarcomere is affected when thin filaments slide past thick filaments during muscle contraction

As thin filaments slide past thick filaments during the sliding filament mechanism of muscle contraction, the sarcomere becomes shorter with each contraction. The action of the sliding filaments draws the Z discs closer together and causes the sarcomere as a whole to shorten as the filaments overlap.

What do skeletal muscle tissue and cardiac muscle tissue share in common?

Both skeletal and cardiac muscle tissues are striated.

What do skeletal muscle contractions share in common with smooth muscle contractions?

Both types of contractions result from thick and thin filaments sliding past one another.

Describe the role of calcium in the regulation of the troponin-tropomyosin complex.

Calcium binds troponin upon its release from the sarcoplasmic reticulum when the skeletal muscle fiber is excited. As a result of the binding, tropomyosin shifts and moves revealing active sites on actin. As the muscle relaxes, calcium ions are pumped back into the sarcoplasmic reticulum. Without calcium, troponin and tropomyosin return to their positions blocking the active sites on actin. Myosin heads are prevented from binding and muscle contraction is inhibited.

Describe the role of calcium in the crossbridge cycle of the sliding filament mechanism.

Calcium ions released from the sarcoplasmic reticulum bind to troponin. Upon binding, tropomyosin moves and the active sites of actin filaments are now exposed. Once the active sites are exposed, crossbridge formation may commence when myosin heads bind to the active sites on the actin filaments. A crossbridge cycle is now initiated in which the thick and thin filaments slide past one another.

Describe the roles of contractile and regulatory proteins in the myofibril

Contractile proteins produce tension while regulatory proteins control when the muscle can contract.

Describe the events of the relaxation period of a muscle twitch

During relaxation, tension decreases as calcium ions are pumped back into the sarcoplasmic reticulum (SR) for storage. Tropomyosin blocks the active sites on actin and the muscle relaxes. Tension eventually equals zero.

Summarize the steps of the crossbridge cycle.

During the crossbridge cycle, a myosin head binds to an active site on actin that leads to the sliding of myofilaments. ATP hydrolysis cocks the myosin head into its high energy position. ADP and a phosphate remain attached to the myosin head. The myosin head binds to an active site on actin. When ADP and the phosphate detach from the myosin head, the power stroke occurs in which myosin pulls actin toward the center of the sarcomere. ATP is needed for the release of the myosin head from actin so that this crossbridge cycle can repeat again

conductivity

Electrical changes travel along the plasma membrane

Define excitability.

Excitability is the ability of a muscle cell to respond to a stimulus.

Tennis elbow is a misnomer for a condition caused by changes in the tendon that attaches the extensor carpi radialis brevis to bone. Discuss the origin and action of this muscle.

Extensor carpi radialis brevis has its origin on the lateral epicondyle of the humerus bone. Its action is to extend the wrist and abduct the hand.

Unipennate muscles have fascicles that wrap around a bone or have a twisted appearance.

False

On a laboratory exam, you are asked to identify various muscle tissues through the microscope. Describe the characteristics you will use to differentiate among the three types of muscle tissue

First, look for light and dark bands known as striations to help you differentiate between striated muscle tissue (cardiac and skeletal) and non-striated muscle tissue (smooth). To determine the difference between the two types of striated muscle tissue, look for long, multinucleated cells that are arranged parallel to one another in skeletal muscle tissue. By contrast, cardiac muscle cells are shorter and wider, branched, and generally have only one or two nuclei. Intercalated discs are unique to cardiac muscle cells. Finally, non-striated muscle tissue is smooth muscle tissue. Smooth muscle cells are long and flattened with two pointed ends (spindle-shaped). These cells often have a single, centrally located oval nucleus

What type of muscle performs an anchoring function by holding a bone in place?

Fixator

Determine how muscles are affected if the muscle receives stimulations so frequently that it has no opportunity to relax between them.

Fused, or complete, tetanus can occur when a muscle receives no opportunity to relax between frequent stimulations. A sustained contraction occurs because the muscle cell has received a stimulus before the last twitch is over.

What best describes fusiform skeletal muscle structure? A) Fusiform muscles are broad and taper to a single tendon. B) Fusiform muscles have fascicles that feather out at one angle from a tendon. C) Fusiform muscles may wrap around a bone or have a twisted appearance. D) Fusiform muscles tend to be thicker in their belly and taper at their ends.

Fusiform muscles tend to be thicker in their belly and taper at their ends.

What purpose do gap junctions serve in cardiac and smooth muscle tissues?

Gap junctions electrically link muscle cells together so that action potentials spread rapidly through the cells. Cells in single-unit smooth muscle contract together as a single unit due to the presence of gap junctions. By contrast, smooth muscle tissue that lacks these gap junctions do not work together and contract as a single unit. Cardiac muscle tissue possesses gap junctions to allow the heart to contract as a unit to act functionally as a pump.

The central region of the A band that lacks thin filaments is the:

H zone

How does hypertrophy change a muscle? Briefly explain.

Hypertrophy is an increase in both the number of myofibrils and the diameter of the muscle fibers.

Describe the bands that create the light and dark areas of skeletal muscle fibers known as striations.

I bands and A bands create the light and dark areas known as striations on a skeletal muscle fiber. I bands, or light bands, contain only thin filaments. These bands are lighter because they allow more light to pass through. A bands, or dark bands, contain thick filaments. The thick filaments block more light than the thin filaments.

Electrical gradients exist because sodium and potassium ions are separated on either side of the plasma membrane.

true

What are the inward extensions of the sarcolemma into the muscle cell called? What function do these extensions serve?

Inward extensions of the sarcolemma are known as transverse tubules (T-tubules). During excitation-contraction coupling, the action potential is carried down the T-tubules into the depths of the muscle fiber to stimulate the release of calcium ions from the terminal cisternae.

What can you tell about a muscle whose name includes the word serratus? A) It is a large muscle. B) Its appearance is serrated or jagged. C) It is a supinator. D) It is located on the medial side of the body.

Its appearance is serrated or jagged.

Jim wants to tone his abdomen and create "six-pack abs." What exercise do you recommend for him? What muscle will he be exercising?

Jim should exercise his rectus abdominis muscle by performing sit-ups, a muscle that performs trunk flexion

Kegel exercises can help a female strengthen muscles of the pelvic floor. Why would a female perform these exercises? What muscle of the pelvic floor is targeted by these exercises?

Kegel exercises can strengthen the external urinary sphincter to prevent urinary incontinence and to guard against pelvic organ prolapse. These exercises target the muscles of the pelvic floor (diaphragm) and muscles in the levator ani group. The levator ani group consists of the pubococcygeus, iliococcygeus, and coccygeus muscles

Which of the following is the action of the levator palpebrae superioris muscle?

Levator palpebrae superioris elevates, or opens, the upper eyelid.

M line

Middle line of the A band

H zone

Middle portion of the A band that contains thick filaments only

Clostridium botulinum is a bacterium that produces botulinum toxin that inhibits the release of acetylcholine. Which description best fits how muscle cells will respond to a lack of acetylcholine?

Muscle cells will become paralyzed when there is a lack of acetylcholine

Latrotoxin, produced by the poisonous black widow spider, increases the release of acetylcholine. How do muscle cells respond?

Muscle cells will experience fused or complete tetanus when excess acetylcholine exists.

Greater muscle tension results when muscle fibers are repeatedly stimulated

true

Explain why myoglobin is useful.

Myoglobin binds oxygen that has diffused into the muscle cell from the extracellular fluid. Oxygen is released from myoglobin as mitochondria perform oxidative catabolism. Oxidative catabolism utilizes oxygen to produce ATP. Thus myoglobin supplements oxygen delivery to mitochondria.

Which statement best describes the function of myoglobin?

Myoglobin stores oxygen in muscle cells

Kelly is examining a myogram showing contractions of the gastrocnemius muscle. Assess how she should differentiate unfused (incomplete) tetanus from fused (complete) tetanus.

On the myogram, although maximum tension can be achieved, the muscle has opportunities to partially relax between contractions. Pulsating tension results (unfused tetanus) in which the muscle relaxes slightly, then tension increases a little more with each successive muscle twitch. Muscles experiencing fused tetanus have no opportunity for relaxation between stimuli since the stimuli arrive more frequently at the muscle (approximately 80-100 stimuli per second). On the myogram, maximum tension would be achieved through fused tetanus while the muscle experiences a sustained contraction without relaxation.

Jack has decided to take up jogging as a way to enhance his endurance training

true

Explain the role sodium ions play in the depolarization stage of the action potential.

Positively charged sodium ions make the membrane potential become less negative during depolarization. Sodium ions rush into a muscle cell with their concentration gradient when voltage-gated sodium ion channels open. The membrane potential reaches a peak of +30 mV.

a band

Region that contains both thick and thin filaments

I band

Region that contains only thin filaments

Mr. Bailey, a 58 year old man, wants to add muscle mass to his frame since he has noticed he is not as strong as he used to be. Discuss the type of physical training you have determined will help him add strength to his muscles. How will your choice help him achieve his goal? What muscle changes do you think he will experience as he begins your training?

Resistance training, or strength training, will help Mr. Bailey add strength to his muscles. Resistance training increases the number of myofibrils, therefore increasing the diameter of the muscle fibers. Thus, his muscles can hypertrophy with this type of exercise. To achieve his goal, Mr. Bailey should use free weights or a resistance-exercise machine. However, a trade-off of muscle hypertrophy is the loss of endurance that comes with the proportionally fewer mitochondria and blood vessels in the muscle tissue compared to the results of endurance training. If he chooses resistance training alone, he may experience a decreased capacity for endurance.

The function of the sarcoplasmic reticulum (SR) is to store and release calcium ions.

true

Speech language pathologists work with patients who have difficulty swallowing. Name the muscles that initiate swallowing and push food into the esophagus, and describe their actions.

Sternohyoid, sternothyroid, omohyoid, and thyrohyoid depress the hyoid and pharynx to push food toward the middle and lower throat while closing off entry to the respiratory tract. These actions are part of the swallowing reflex.

In physical education class, Miguel is performing jumping jacks. He abducts his arms and thighs in unison, and then adducts them. Determine the muscles responsible for abduction and adduction of the arms and thighs.

Supraspinatus and deltoid perform arm abduction while latissimus dorsi, pectoralis major, teres major, coracobrachialis and subscapularis perform arm adduction. Gluteus maximus, medius, and minimus, and piriformis perform abduction of the thigh while adductor magnus, adductor longus, adductor brevis, pectineus and gracilis perform adduction of the thigh.

While climbing stairs in the football stadium, Gary injured his calcaneal tendon (Achilles tendon). Describe the muscles and action(s) that are affected. From what action and activities should he refrain while his tendon heals?

The calcaneal tendon (Achilles tendon) attaches the two heads of gastrocnemius and soleus muscles to the posterior surface of the calcaneus (heel bone). These muscles form the triceps surae group and are responsible for plantar flexion. While his calcaneal tendon heals, Gary should refrain from activities that plantar flexes the injured foot, such as walking stairs, standing on his toes or jumping.

Angie received an injection in her deltoid muscle. Her arm is now sore and she refuses to move it. What action can she not perform?

The deltoid muscle is the prime mover, or agonist, of arm abduction.

Susie raised her eyebrows and dropped her jaw open in excitement when she walked in to her surprise birthday party. Determine and describe the muscles involved in these facial expressions.

The epicranial aponeurosis, which includes the frontalis and occipitalis muscles, raises the eyebrows and skin of the forehead into horizontal wrinkles, as we do when looking surprised. The platysma muscle is found in the neck. It produces the open-mouthed, "jaw-dropping" look of surprise.

Discuss the naming scheme and location of the external oblique, internal oblique, and transversus abdominis muscles.

The fibers of the external oblique run at an angle. This superficial muscle is situated lateral to the rectus abdominis. Internal oblique is found deep to external oblique, but its fibers run opposite and nearly perpendicular to those of external oblique. The transversus abdominis muscle is the deepest abdominal muscle and has horizontal fibers

In the human body, what is the fulcrum in a lever system?

The fulcrum is the joint at which movement occurs.

A football player sustained an injury to his hamstring group. What muscles belong to the hamstring group and what would be the effect of the injury on this group?

The hamstring group consists of the biceps femoris, semitendinosus, and semimembranosus muscles. Since these muscles work together to extend the thigh and flex the knee, the football player would have difficulty walking or running.

Explain how the hamstring and quadriceps femoris groups work as antagonists to one another. What action depends on the coordination of these groups?

The hamstring group flexes the leg at the knee joint while the quadriceps femoris group extends or straightens the leg at the knee. These two groups are critical for walking in which the leg is flexed and extended at the knee joint

Describe the origins and insertions of the masseter and temporalis muscles. What action do these muscles work synergistically to accomplish?

The masseter muscle is a thick, band-like muscle that has its origin on the zygomatic arch. It inserts on the angle and lateral surface of the ramus of the mandible. It covers much of the ramus of the mandible. The temporalis muscle is a fan-shaped, convergent muscle that has its origin on and spreads over the flat portion of the temporal bone. It inserts on the coronoid process of the mandible. These two muscles provide much of the force needed for elevating the mandible to bite and chew food.

Briefly discuss the role of the myosin heads in the sliding filament mechanism of muscle contraction.

The interaction of thin filaments sliding past thick filaments generates tension throughout the sarcomere during muscle contraction. This is known as the sliding filament mechanism. Myosin heads of the thick filaments grab active sites on thin filaments and pull the thin filaments toward the M line as the myosin heads rotate. The pulling action brings the Z discs closer together and shortens the sarcomere. Neither the thin nor the thick filaments actually shorten; instead the thin filaments are pulled and slide toward the M line.

List the muscles of the levator ani group and provide the function of this group.

The levator ani group consists of pubococcygeus, iliococcygeus, and coccygeus. This group of muscles supports the pelvic floor (diaphragm), anal canal, and genitourinary organs.

During abdominal surgery, the surgeon makes a cut lateral to the linea alba. Discuss the location of the linea alba and the muscle that has been cut.

The linea alba is a line of connective tissue along the midline of the abdomen. The linea alba separates the left and right rectus abdominis muscles. These superficial muscles run the length of the anterior abdominal area.

What is accomplished by the power stroke?

The power stroke results in myosin heads pulling actin toward the center of the sarcomere.

During a baseball game, Eddie experienced a rotator cuff injury that benched him for the rest of the season. Eddie's doctor said he would be sitting out to let the SITS muscles heal. What four muscles did his doctor reference?

The rotator cuff consists of four muscles: supraspinatus, infraspinatus, teres minor, and subscapularis, otherwise known as the SITS muscles. These muscles hold the shoulder joint together during forceful movements that could damage the joint.

z disc

The sarcomere is situated between two of these adjacent structures

What is the function of the sarcoplasmic reticulum?

The sarcoplasmic reticulum (SR) stores and releases calcium ions

Describe the synaptic cleft.

The synaptic cleft is the narrow gap of space between the axon terminal and the muscle fiber into which acetylcholine is released.

Explain the meaning of the muscle name extensor carpi ulnaris

The term extensor indicates this muscle increases the angle between bones through extension. Both carpi and ulnaris indicate a specific body region. Carpi indicates the wrist region while ulnaris indicates one of the bones of the forearm.

Explain the medial to lateral placement of the muscle groups of erector spinae.

The three groups of the erector spinae are named in order of their medial-lateral placement relative to the axis of the vertebral column. The spinalis group is located closest to the center of the vertebral column, just to the sides of the spinous processes of the spine. The longissimus group is slightly lateral to the spinalis group. The iliocostalis group is the most lateral.

z-disc

Thin and elastic filaments are anchored to this structure

Describe how third-class levers operate in terms of force moved and speed of movement.

Third-class levers have a mechanical disadvantage in terms of force. The fulcrum in a third-class lever is located closer to the applied force and farther from the load moved. Although third-class levers are disadvantaged in terms of force, they produce a speedy movement.

z-disc

This structure attaches myofibrils to one another

Gowoon wants to be a long-distance runner and participate in competitions on her high school track and field team. Describe the specific type of skeletal muscle fiber which will help her excel at her sport. What type of training should she perform to enhance the capabilities of this particular fiber type?

Type I fibers are slow-twitch fibers that can maintain extended periods of contraction. Since these fibers use large quantities of ATP to maintain contractions, they utilize oxidative catabolism. Oxidative catabolism can provide ATP for hours. Myoglobin present in these muscle fibers binds oxygen to help supply the oxidative generation of ATP. Gowoon should focus on endurance training which will result in an increase in the number of mitochondria and a greater blood supply (more blood vessels). Endurance training helps type I muscles utilize resources to make ATP and resist fatigue.

Discuss the type of contractions produced by type I muscle fibers.

Type I muscle fibers are slow-twitch fibers. Although contractions are slower and less forceful, Type I fibers can maintain contractions over extended periods of time as they are slow to fatigue.

The deltoid is responsible for:

abducting the arm.

Identify the rectus abdominis muscle.

abs

During muscle contraction, myosin crossbridges bind to active sites on:

actin

Damage to the pectoralis major would interfere with a person's ability to:

adduct the humerus

Which of the following muscles is named for its action? A) deltoid B) gluteus maximus C) biceps brachii D) adductor magnus

adductor magnus

Triceps brachii and biceps brachii perform opposing actions and are classified as:

antagonists

Identify the biceps femoris muscle.

armpit

What influences the appearance and function of skeletal muscle? A) arrangement of the pattern of fascicles B) number of muscle cells in a motor unit C) presence of perimysium around fascicles D) presence of endomysium around muscle cells

arrangement of the pattern of fascicles

In response to physical inactivity, we expect to see muscles:

atrophy

Identify the lateral rectus muscle

attaches eye

Muscles with a triangular shape, such as the pectoralis major muscle in the chest, typically have a:

convergent fascicle arrangement.

The main immediate source of ATP (lasting about 10 seconds) as muscle contractions begin comes from:

creatine phosphate.

The binding of a myosin head to an actin molecule is termed a:

crossbridge.

During excitation-contraction coupling, calcium ion concentration is highest in the

cytosol of the muscle fiber.

The loss of potassium ions from the cell during the repolarization stage restores a membrane potential of -85 mV.

true

What joint serves as the fulcrum when triceps brachii moves the forearm?

elbow joint

Which of the following wraps and surrounds an individual skeletal muscle fiber?

endomysium

Where is the origin of the frontalis muscle?

epicranial aponeurosis

During the recovery period after exercise, we breathe deeper and faster. This increased rate of respiration is known as

excess postexercise oxygen consumption (EPOC).

When an action potential arrives in an axon terminal, synaptic vesicles containing acetylcholine are released by

exocytosis

Damage to the trapezius would cause a person to have difficulty

extending the head

The degree to which a muscle cell can stretch depends on its:

extensibility

Which muscle provides voluntary control of defecation?

external anal sphincter

Which of the following is NOT a muscle of respiration?

external oblique

From superficial to deep, the three muscles of the lateral abdominal wall are:

external oblique, internal oblique, transversus abdominis.

Identify the corrugator supercilii muscle

eyebrow bone

A first-class lever has the fulcrum situated farther from the point of the applied force, with the load to be moved in between.

false

Both isotonic eccentric contractions and isotonic concentric contractions shorten the muscle.

false

Cardiac muscles perform peristalsis to pump blood through the heart.

false

Contractility is the ability of a muscle to shorten.

false

Creatine phosphate provides 30-40 seconds of energy for muscle activity.

false

In a sarcomere, the light and dark bands are produced by alternating M lines and Z discs.

false

Myofilaments shorten to produce muscle contractions according to the sliding filament mechanism.

false

Skeletal muscle fibers possess intercalated discs.

false

The Na+/K+ ATPase (Na+/K+ pump) maintains the concentration gradients for sodium and potassium ions by moving two sodium ions out of the cell and three potassium ions into the cell.

false

The entry of acetylcholine into a muscle cell through ligand-gated ion channels depolarizes the sarcolemma locally.

false

The external urinary sphincter provides involuntary control of urination

false

The medial rectus muscle and lateral rectus muscle pull the eye in the same direction.

false

The prime mover of elbow flexion is biceps brachii.

false

When climbing stairs, the gluteus maximus and hamstring group muscles work as antagonists.

false

A group of skeletal muscle fibers together with the surrounding perimysium form a(n):

fascicle.

What lever class has the fulcrum situated between the force and the load?

first-class lever

What is the action of flexor carpi ulnaris?

flex the wrist

When muscle fibers are stimulated so frequently they do not have an opportunity to relax, they are experiencing:

fused or complete tetanus.

When climbing stairs, which muscles plantar flex your foot?

gastrocnemius and soleus

What is the basic function of all muscle tissue?

generate muscle tension

What is a necessary reactant for glycolytic, or anaerobic, catabolism to proceed?

glucose

Identify the brachialis muscle.

inner arm

Sartorius

inner thigh (2)

Which muscle abducts the thigh, medially rotates the thigh, and stabilizes the pelvis during walking?

gluteus minimus

A pathway of ATP production that results in the formation of lactic acid is:

glycolytic catabolism.

Where does infraspinatus insert?

greater tubercle of the humerus

Semitendinosus

hamstring (6)

When climbing stairs, which muscle or muscle group flexes your knee?

hamstring group

Iliopsoas is formed by the union of two muscles known as:

iliacus and psoas major.

Which muscle is a powerful agonist of adduction and medial rotation of the arm?

latissimus dorsi

) Which muscle works as an antagonist to orbicularis oculi?

levator palpebrae superioris

What is NOT a bone to which the sternocleidomastoid muscle is attached?

mandible

Medial rotation of the eyeball is performed by the:

medial rectus muscle.

Where are receptors for acetylcholine located?

motor end plate

A single motor neuron together with all the skeletal muscle fibers it innervates is called a:

motor unit

Muscular walls of the thorax and abdomen are composed of:

oblique and rectus muscles

Which of the following promotes the depolarization stage?

opening of voltage-gated sodium ion channels and sodium ions enter the cell

Which of the following muscles is NOT associated with the mouth?

orbicularis oculi

John experienced a cut that severs the tendon that attaches the insertion of the gastrocnemius muscle. As a result of this injury, what action is difficult for him to perform?

plantar flexion

Fibularis longus

outer calf (4)

External oblique

outer stomach (7)

Through which ATP-generating mechanism can long-lasting muscle contractions be sustained

oxidative catabolism

Which muscle adducts the fingers?

palmar interossei

List and summarize the five patterns of fascicles seen in skeletal muscles.

parallel muscle has evenly spaced fascicles attaching to a tendon that is about the same width as the muscle. convergent muscle is a broad muscle that uniformly tapers to a single tendon pennate muscle has fibers and fascicles that attach to a tendon at an angle in such a way that it resembles a feather spiral muscle may wrap around a bone or have the twisted appearance of towel wrung out to dry. Fusiform muscles tend to be thicker in their belly and tapered at their ends.

The vastus lateralis, vastus medialis, and vastus intermedius muscles insert on the:

patella and tibial tuberosity of the tibia

Between the start of the latent period and the start of the contraction period, there is a time interval during which the muscle cannot respond to another stimulus. This brief period is known as the

refractory period.

What does the depolarization of the transverse tubules (T-tubules) promote?

release of calcium from the sarcoplasmic reticulum

The Na+/K+ pump helps a muscle cell maintain a state of:

resting membrane potential

The plasma membrane of a muscle cell is known as the:

sarcolemma.

What is the functional contractile unit of the myofibril?

sarcomere

What part of the myofibril shortens to produce contractions of the muscle fiber? A) sarcomere

sarcomere

The storage and release of calcium ions is the key function of the

sarcoplasmic reticulum

Standing on tiptoes is an example of a:

second-class lever system

From medial to lateral, what are the muscles of the hamstring group?

semimembranosus, semitendinosus, biceps femoris

Infraspinatus

shoulder (3)

Where does the mentalis muscle insert?

skin of the chin

Type I fibers lack

speed.

How do most circular muscles function?

sphincters

What is the proper position of the erector spinae muscles situated from medially to laterally relative to the axis of the vertebral column?

spinalis, longissimus, iliocostalis

Which of the following is NOT a muscle involved in the movement of the tongue to manipulate food while chewing and pushing the bolus of food into the throat

stylohoid

Damage to the stylohyoid, mylohyoid, and geniohyoid impairs:

swallowing

Which type of muscle works together with the agonist?

synergist

Which of the following is NOT a muscle of the rotator cuff?

teres major

When a skeletal muscle fiber contracts:

the H zone and I bands narrow

What happens when troponin and tropomyosin block the active sites of actin?

the muscle relaxes

ATP is required for a power stroke to be repeated during the contraction cycle.

true

A lever system works at a mechanical advantage when:

the fulcrum is located farther from the applied force

Which of the following statements is the most accurate description of the sliding filament mechanism?

thin filaments slide past thick filaments towards the M line

A muscle that dorsiflexes the foot is the:

tibialis anterior

Which muscle is an antagonist to the gastrocnemius muscle?

tibialis anterior

Deep inward extensions of the sarcolemma form a tunnel-like network inside the muscle cell known as:

transverse tubules (T-tubules

Which muscles elevate the scapula?

trapezius and levator scapulae

Which of the following extends the elbow?

triceps brachii